linux-kernel - Re: [PATCH v4 12/13] mips: csrc-r4k: Mark R4K timer as unstable if CPU freq changes

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Message-ID: <20200522072957.GH7331@alpha.franken.de>
Date:   Fri, 22 May 2020 09:29:57 +0200
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc:     Serge Semin <fancer.lancer@...il.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Paul Burton <paulburton@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Alexander Lobakin <alobakin@...nk.ru>,
        Huacai Chen <chenhc@...ote.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 12/13] mips: csrc-r4k: Mark R4K timer as unstable if
 CPU freq changes

On Thu, May 21, 2020 at 05:07:23PM +0300, Serge Semin wrote:
> Commit 07d69579e7fe ("MIPS: Don't register r4k sched clock when CPUFREQ
> enabled") disabled the r4k-clock usage for scheduler ticks counting due
> to the scheduler being non-tolerant for unstable clocks sources. For the
> same reason the clock should be used in the system clocksource framework
> with care. As soon as CPU frequency changes the clocksource framework
> should be notified about this by marking the R4K timer being unstable
> (which it really is, since the ticks rate has been changed synchronously
> with the CPU frequency).
> 
> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> Cc: Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>
> Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
> Cc: Paul Burton <paulburton@...nel.org>
> Cc: Ralf Baechle <ralf@...ux-mips.org>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: devicetree@...r.kernel.org
> ---
>  arch/mips/Kconfig           |  1 +
>  arch/mips/kernel/csrc-r4k.c | 40 +++++++++++++++++++++++++++++++++++++
>  2 files changed, 41 insertions(+)

applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]